Rotor hub elastomeric bearing

ABSTRACT

An apparatus comprising a drivelink comprising a housing including a socket, wherein the socket comprises a cross-sectional area, and a bearing cartridge disposed within the socket, wherein a cross-sectional area of the cartridge is less than the cross-sectional area of the socket. An apparatus comprising a drivelink comprising a housing having a socket, and a bearing cartridge positioned within the socket and comprising a first portion and a second portion, wherein the first portion is configured to undergo compression when a load is applied to the drivelink, and wherein the second portion is configured to not be in tension when the load is applied to the drivelink.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 13/800,440, entitled “Rotor Hub ElastomericBearings”, filed Mar. 13, 2013. The entire contents is incorporated byreference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not applicable.

BACKGROUND

The disclosure pertains to helicopter rotors and to drivelinks forincorporation within helicopter rotors. Rotor systems may incorporatedrivelinks for transferring torque between a drive shaft and drivenshafts that rotate about misaligned axes. For example, a multilink jointcomprising a plurality of drivelinks may be incorporated in a helicopterrotor assembly in order to reduce and/or normalize kinematic errorsintroduced during operation of the rotor assembly (e.g., oscillatorystrain, lateral wobbling, etc.). Examples of such are found in U.S. Pat.No. 5,186,686 and U.S. Pat. No. 4,729,753, both of which areincorporated herein by reference. Such multilink joint may comprise awobble plate and a plurality of drivelinks coupling drive link trunnionsto the wobble plate.

The drivelinks may comprise elastomeric bearings in order to enablemovement of the wobble plate within a predetermined, limited range ofmotion. However, problems arise when constructing an elastomeric bearingthat is resilient enough to reduce and/or normalize kinematic error, andwhich is also strong enough to carry the operational loads. Moreparticularly, problems arise because as elastomeric material is madestronger, its resiliency decreases. As a result, in previous systemscomprising drivelinks as the elastomeric bearings are compressed so asto transfer torque loads, the backside of the bearings experienceharmful tension (e.g., one side of the bearing is put in compression andthe other side of the bearing is put in tension). The tension can pullapart the elastomeric material or the layers of elastomeric material andmetal within the bearings, which degrades bearing performance.Therefore, needed is driveshaft comprising an elastomeric bearing thatoffers effective kinematic performance without experiencing tension.

SUMMARY

In an embodiment, an apparatus is provided. The apparatus comprises adrivelink comprising a housing including a socket, wherein the socketcomprises a cross-sectional area, and a bearing cartridge disposedwithin the socket, wherein a cross-sectional area of the cartridge isless than the cross-sectional area of the socket.

In an embodiment, an apparatus is provided. The apparatus comprises adrivelink comprising a housing having a socket, and a bearing cartridgepositioned within the socket and comprising a first portion and a secondportion, wherein the first portion is configured to undergo compressionwhen a load is applied to the drivelink, and wherein the second portionis configured to not be in tension when the load is applied to thedrivelink.

In an embodiment, disclosed is a method comprising providing a drivelinkcomprising a housing having a socket, and a bearing cartridge positionedwithin the socket and comprising a first portion and a second portion,wherein the first portion is configured to undergo compression when aload is applied to the drivelink, and wherein the second portion isconfigured to not be in tension when the load is applied to thedrivelink.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of the disclosed embodiments, reference willnow be made to the accompanying drawings in which:

FIG. 1 is a perspective view of an embodiment of a helicopter having adrivelink.

FIG. 2 is a perspective view of an embodiment of a rotor hub system.

FIG. 3 is a perspective view of a drivelink according to an embodiment.

FIG. 4 is a top view of the drivelink as shown in FIG. 3.

FIG. 5 is a cross-sectional view of the drivelink taken along line 5-5in FIG. 3.

FIG. 6 is a perspective of the cross-sectional view from FIG. 5.

FIG. 7 is cross-sectional view taken along line 6-6 in FIG. 7.

FIG. 8 is a perspective view of a drivelink according to anotherembodiment.

FIG. 9 is a flowchart illustrating a method of manufacturing a drivelinkaccording to the embodiment illustrated in FIG. 3.

FIG. 10 is an illustration of the drivelink as shown in FIG. 3 beforethe cartridges are inserted into the housing.

FIG. 11 is a flowchart illustrating a method of manufacturing adrivelink according to the embodiment illustrated in FIG. 7.

DETAILED DESCRIPTION

It should be understood at the outset that although an illustrativeimplementation of one or more embodiments are provided below, thedisclosed systems and/or methods may be implemented using any number oftechniques, whether currently known or in existence. The disclosureshould in no way be limited to the illustrative implementations,drawings, and techniques illustrated below, including the exemplarydesigns and implementations illustrated and described herein, but may bemodified within the scope of the appended claims along with their fullscope of equivalents.

Described herein is a drivelink comprising sockets and elastomericbearings disposed within the sockets. The elastomeric bearings may beconfigured such that they offer effective strength and compressionproperties without experiencing tension. In doing so, the elastomericbearings may be pre-loaded so that the cross-sectional area of eachbearing is less than the cross-sectional area of a socket in which it isplaced. The amount of pre-loading may be substantially equal to theamount of deformation expected to be experienced by the elastomericbearing upon compression thereof. Thus, prior to operation a spacing maybe located within the socket and proximate the elastomeric bearing. Inoperation as the elastomeric bearing is compressed, the elastomericbearing may deform so as to occupy the location of the spacing. Becausethe elastomeric bearing may deform into the location of the spacing,compression of the front side of the elastomeric bearing does not exerttension on the back side of the elastomeric bearing. Therefore, thedisclosed drivelink offers superior strength and compressioncapabilities and has a prolonged lifespan.

FIG. 1 is a perspective view of a helicopter 40. Certain embodiments ofthe disclosure may be used with a helicopter such as helicopter 40.However, it should be understood that the helicopter example is givenmerely for illustration purposes only. Embodiments of the presentdisclosure are not limited to any particular setting or application, andembodiments can be used with a drive system in any setting orapplication such as other aircrafts (e.g., airplanes, tiltrotors, etc.),vehicles, or equipment.

In an embodiment, the helicopter 40 includes a main rotor assembly 50, atail rotor assembly 60, a fuselage 68, and landing gear 70. The mainrotor assembly 50 includes two or more blades 52 that are rotated aboutan axis of rotation 54 in either a clockwise direction or acounterclockwise direction as indicated by arrow 56. The main rotorassembly 50 generates a lift force that supports the weight ofhelicopter 40 and a thrust force that counter acts aerodynamic drag.Additionally, the main rotor assembly 50 can also be used to inducepitch and roll of the helicopter 40. The tail rotor assembly 60 includestwo or more blades 62 that are rotated about an axis of rotation 64 ineither a clockwise direction or a counterclockwise direction asindicated by the arrow 66. The tail rotor assembly 60 counters thetorque effect created by the main rotor assembly 50 and allows a pilotto control the yaw of the helicopter 40. The fuselage 68 is the mainbody section the helicopter 40. Optionally, the fuselage 68 holds thecrew, passengers, and/or cargo and houses the engine, transmission,gearboxes, drive shafts, control systems, etc. that are needed toestablish an operable helicopter. The landing gear 70 is attached to thefuselage 68, supports the helicopter 40 on the ground, and allows it totake off and land.

In FIG. 2, a rotor hub system 90 is illustrated. In such an embodiment,the rotor hub system 90 may generally comprise a mast 89, a plurality ofdrivelinks 100, a hub assembly 82, and a yoke 81. In an embodiment, therotor hub system 90 is configured to rotate about the mast 89. In anembodiment, the mast 89 may be configured to transfer a rotational forceand/or torque (e.g., from a transmission, a drive system, etc.) to therotor hub system 90. In an embodiment, the mast 89 may generallycomprise one or more interfacing surfaces (e.g., splines, grooves, etc.)and may extend along a longitudinal axis 5. In an embodiment, thediameter of the mast 89 may be sized for an application (e.g., anaircraft) as would be appreciated by one of ordinary skill in the artupon viewing this disclosure.

FIGS. 3-6 illustrate a drivelink 100 according to an embodiment. Thedrivelink 100 may comprise a housing 104, a first bearing cartridge 101,and a second bearing cartridge 111. The housing 104 may comprise a firstsocket 105 and a second socket 106. The housing 104 may be configured ina dog bone shape when viewed from the side (best seen in FIGS. 3, 5, and6), wherein the two sockets 105, 106 are coupled via a center portion125 of the housing 104 that is not as thick as the two sockets 105, 106.The first socket 105 may comprise a generally cylindrical cavity locatedat a distal end of the housing 104, while the second socket 106 maycomprise another generally cylindrical cavity located at a proximate endof the housing 104. As seen in FIGS. 5, and 6, the sockets 105, 106 maybe wider at a center portion within the housing 104 than they are at thetop and bottom surface of the housing 104 (the arcuate shape discussedbelow), although such a feature is not required. The housing 104 maycomprise a metallic material, such as steel or titanium, or any othersuitable material.

The first socket 105 may be configured to support the first bearingcartridge 101, and the second socket 106 may be configured to supportthe second bearing cartridge 111. Each bearing cartridge 101, 111 maycomprise an outer component 120 comprising an outer elastomeric member102(a) and an outer race 103(a), and an inner component 121 comprisingan inner elastomeric member 102(b) and an inner race 103(b). Theelastomeric materials 102(a), 102(b) may be any suitable elastomericmaterial, such as rubber, vulcanized rubber, or alternating layers ofrubber and metal. Each bearing cartridge 101, 111 may have a trunnionrace 107, 108, respectively, positioned between the outer component 120and the inner component 121. The first trunnion race 107 may comprisethree apertures for supporting a clocking bearing, while the secondtrunnion race 108 may comprise a single aperture for supporting arotating bearing. The races 103(a), 103(b) and trunnion races 107, 108may comprise any suitable material, including a metallic material suchas titanium or steel.

The dimensions of the cartridges 101, 111 relative to the housingsockets 105, 106 may be of particular significance and will now bedescribed. FIGS. 3 and 4 illustrate the drivelink 100 in an uncompressedstate. In this uncompressed state, the cross-sectional area (when viewedfrom above as in the FIG. 4 illustration) of the first socket 105 isgreater than the cross-sectional area of the first bearing cartridge101, and the cross-sectional area (when viewed from above as in the FIG.4 illustration) of the second socket 106 is greater than thecross-sectional area of the second bearing cartridge 111. As a result, aspacing 117 is located within each socket 105, 106. For example, in theembodiment shown in FIGS. 3 and 4, two spacings 117 are located withinthe first socket 105 between the outer component 120 and the innercomponent 121, and two spacings 117 are located within the second socket106 between the outer component 120 and the inner component 121.

The elastomeric members 102(a), 102(b) may each deform a substantiallypredetermined amount in response to compression forces exerted thereon.The elastomeric members 102(a), 102(b) may be engineered so that whenthey experience compression forces from the drive, the elastomer members102(a), 102(b) deform to possess an area substantially equal to the areawithin the socket 105, 106. Thus, the cartridges may be pre-loaded sothat the pre-compression is substantially equal to the expecteddeformation. For example, when the first bearing cartridge 101 iscompressed, the first bearing cartridge 101 may deform to fill the firstsocket 105 and thereby occupy the area where the spacings 117 werelocated prior to the compression. Likewise, when the second bearingcartridge 111 is compressed, the second bearing cartridge 111 may deformto fill the second socket 106 and thereby occupy the area where thespacings 117 were located prior to the compression. While thecompression of the drivelink 100 is described herein, it will beappreciated that a similar effect will occur when the drivelink isplaced in tension.

In some embodiments, the spacings 117 may be located along an axisperpendicular to loads exerted on the drivelink 100. For example, FIG. 4includes two arrows that may represent the directions of a substantialamount of the load exerted on the drivelink 100. As a result, the arrowsmay represent the directions of a substantial amount of compressionexperienced by the cartridges 101, 111. Therefore, as the cartridges101, 111 are compressed, they may deform into the spacings 117 andthereby take on a shape that is substantially identical to the areawithin the sockets 105, 106.

However, the spacings 117 need not be aligned perpendicularly to theexerted loads and may be located anywhere within the sockets 105, 106.Moreover, in some embodiments each cartridge 101, 111 may comprise onlyone spacing 117 instead of two spacings 117. In some embodiments, one ofthe two cartridges 101, 111 comprises one spacing 117 while the other ofthe two cartridges 101, 111 comprises more than one spacing 117.

Other alternative embodiments are also included herein. Although theembodiment depicted in FIGS. 3 and 4 comprises components 120, 121 ofsubstantially equal size, in other embodiments the outer component 120may comprise a first size while the inner component 121 comprises asecond size. In some embodiments, the outer component 120 may comprise afirst resilience while the inner component 121 comprises a secondresilience. For example, the outer component 120 may be made of adifferent elastomeric composition with different spring rates than theinner component 121. Further, while FIGS. 3 and 4 illustrate eachcartridge 101, 111 comprising two components 120, 121, it will beappreciated that the cartridges 101, 111 may comprise any number ofcomponents while remaining within the scope of the present disclosure.In some embodiments, the cartridges 101, 111 may comprise an equalnumber of components. In other embodiments, one of the two cartridges101, 111 may comprise a first number of components while the other ofthe two cartridges 101, 111 comprises a second number of components.

In some embodiments, each of the components within a cartridge 101, 111are of substantially equal size. In other embodiments, a cartridge 101,111 may comprise a plurality of components of various sizes. In someembodiments, at least two components within a cartridge 101, 111 are ofsubstantially equal size. In other embodiments, each component within acartridge 101, 111 may be a different size than all of the othercomponents within the cartridge 101, 111. In some embodiments, each ofthe components within a cartridge 101, 111 are of substantially equalresilience. In other embodiments, a cartridge may comprise a pluralityof components of various resiliencies. In some embodiments, at least twocomponents within a cartridge 101, 111 are of substantially equalresilience. In other embodiments, each component within a cartridge 101,111 may be a different resilience than all of the other componentswithin the cartridge 110, 111.

The drivelink 100 may comprise securing means to retain the cartridges101, 111 within their respective sockets 105, 106. In some embodiments(e.g., the embodiment illustrated in FIGS. 3-6) the securing meanscomprises a pin 112, although other means for securing the cartridges101, 111 within the housing 104 may be acceptable. In the embodiment ofFIGS. 3-6, the housing 104 may comprise at least one aperture 109proximate to each socket 105, 106, and the cartridges 101, 111 may eachcomprise at least one aperture 110 corresponding to a socket aperture(e.g., an aperture 110 through the first bearing cartridge 101 maycorrespond in alignment to an aperture 109 through the first socket 105,while an aperture 110 through the second bearing cartridge 111 maycorrespond in alignment to an aperture 109 through the second socket106). The cartridges 101, 111 may be positioned such that the aperture110 through each cartridge 101, 111 aligns with the aperture 109 throughthe housing 104 at each socket 105, 106. Thus, a pin 112 may be insertedthrough the aperture 109 in the housing 104 and through thecorresponding aperture 110 in the cartridge 101, 111. In turn, the pins112 may prevent movement of the cartridges 101, 111 within the sockets105, 106. FIGS. 5 and 6 illustrate cross-sectional views of a drivelink100 comprising a pin 112 extending through each housing aperture 109 andcartridge aperture 110.

Although FIGS. 5 and 6 disclose securing means comprising pins 112 andapertures 109, 110, it will be understood that other securing means maybe used to secure the cartridges 101, 111 within the sockets 105, 106while remaining within the scope of the present disclosure. For example,instead of the pins 112 and apertures 109, 110 or in addition to thepins 112 and apertures 109, 110, securing means may comprise an adhesivematerial (not shown) disposed between a surface of a cartridge 101, 111and a peripheral surface 118, 119 of the housing 104 and/or between asurface of a cartridge 101, 111 and a surface of a trunnion race 107,108. As another example, the securing means may comprise tabs (notshown) extending into a cartridge 101, 111 to prevent movement thereof.

The drivelink 100 may also be shaped to secure the cartridges 101, 111within the housing 104. For example, as seen in FIGS. 5 and 6, thesockets 105, 106, races 103(a), 103(b), elastomeric members 102(a),102(b), and trunnion races 107, 108 may each comprise an upper portion,a lower portion, and a middle, arcuate portion that is greater inoverall width than the upper portion and lower portion. For example, thefirst inner periphery 118 of the housing 104 may comprise an arcuateportion corresponding to an arcuate portion 113 of the outer race 103(a)and to a convex portion 114 of the outer elastomeric member 102(a). Thearcuate portions dimension the first bearing cartridge 101 such that thewidth of the middle portion of the elastomeric members 102(a) is greaterthan the upper portion and lower portion of the sockets 105. Thus, thearcuate portions may prevent the first bearing cartridge 101 fromsliding out of the housing 104. Also, the outer elastomeric member102(a) may also comprise a concave portion 116 that corresponds to aconvex portion 115 of the first trunnion race 107, thereby furthersecuring the first bearing cartridge 101 to the first trunnion race 107and within the first socket 105. While FIGS. 5 and 6 show an embodimentwherein both cartridges 101, 111 comprise arcuate portions that areidentical to one another, one skilled in the art will recognize that thefirst bearing cartridge 101 may comprise arcuate portions dissimilar toarcuate portions of the second bearing cartridge 111. Also, in someembodiments, the first bearing cartridge 101 comprises arcuate portionswhile the second bearing cartridge 111 does not comprise arcuateportions, or, in other embodiments, the second bearing cartridge 111comprises arcuate portions while the first bearing cartridge 101 doesnot comprise arcuate portions. In yet other embodiments, neither thefirst bearing cartridge 101 nor the second bearing cartridge 111comprises arcuate portions.

Now turning to FIGS. 7 and 8, shown is a drivelink 200 according toanother embodiment. The drivelink 200 comprises a housing 204 comprisinga first socket 205 formed within a first inner periphery 218 of thehousing 204, and a second socket 206 formed within a second innerperiphery 219 of the housing 204. In the embodiment shown in FIGS. 7 and8, the drivelink 200 does not include a race, but rather a first pair ofelastomeric members 202(a), 202(b) adhere directly to the outerperiphery 218 and optionally the trunnion race 207, 208 while a secondpair of elastomer members 202(a), 202(b) adhere directly to the innerperiphery 219 and optionally the trunnion race 207, 208.

While the housing 204 and trunnion races 207, 208 may be made of anysuitable material, in the embodiment illustrated in FIGS. 7 and 8, thehousing 204 and trunnion races 207, 208 comprise a metallic material,such as titanium or steel. The elastomeric members 202(a), 202(b) maycomprised vulcanized rubber that is cured while it is within the sockets205, 206. Because the rubber vulcanizes as it cures within the housing,the crosslinking introduced by the vulcanization process creates astrong bond between the rubber and the housing 204. As a result, thecured rubber forms elastomeric members 202(a), 202(b) possessing highresilience and strength and that remain tightly secured to the housing204.

The elastomeric members 202(a), 202(b) may comprise spacings 217. Thespacings 217 may be sized so that, in operation, when the first pair ofelastomeric members 202(a), 202(b) are compressed and thereby becomedeformed, the area of the deformed elastomeric members 202(a), 202(b)becomes substantially equal to the area of the first socket 205.Likewise, in operation, when the second pair of elastomeric members202(a), 202(b) are compressed and thereby become deformed, the area ofthe deformed elastomeric members 202(a), 202(b) becomes substantiallyequal to the area of the second socket 206. As a result, the compressedcartridges offer improved kinematic properties without experiencingtension.

In some embodiments, the spacings 217 may be located along an axisperpendicular to loads exerted on the drivelink 200. Therefore, as theelastomeric members 202(a), 202(b) are compressed, they may deform intothe spacings 217 and thereby take on a greater dimension that issubstantially equal to the area within the sockets 205, 206. However,the spacings 217 need not be perpendicular to the exerted loads and maybe located anywhere within the sockets 205, 206. Moreover, in otherembodiments each pair of elastomeric members 202(a), 202(b) may compriseonly one spacing 217 instead of two spacings 217. In other embodiments,one of the two cartridges 101, 111 comprises one spacing 117 while theother of the two cartridges 101, 111 comprises two spacings 117. In anembodiment comprising only one spacing 217, only one spacer 222 may beinserted into a socket 205, 206 before the curing process or,alternatively, the first and second spacers 222 may be inserted directlybeside one another within the socket 205, 206.

Although the embodiment depicted in FIGS. 7 and 8 comprises elastomericmembers 202(a), 202(b) of substantially equal size, in other embodimentsthe outer elastomeric member 202(a) may comprise a first size while thesecond elastomer member 202(b) comprises a second size.

In some embodiments, the outer elastomeric member 202(a) may comprise afirst resilience while the inner elastomeric member 202(b) comprises asecond resilience. For example, the outer elastomeric member 202(a) maybe made of a different uncured rubber with different spring rights thanthe inner elastomeric member 202(b). Alternatively, the outer and innerelastomeric members 202(a), 202(b) may be made from the same type ofuncured rubber but a curative added to the outer elastomeric member202(a) may be different than a curative added to the inner elastomericmember 202(b) and/or a different amount of curative may be added to theouter elastomeric member 202(a) than to the inner elastomeric member202(b). In some embodiments, the outer elastomeric member 202(a) andinner elastomeric member 202(b) are made of different types of uncuredrubber and also a different type and/or amount of curative is added eachelastomeric member 202(a), 202(b).

Further, while FIGS. 7 and 8 illustrate each socket 205, 206 comprisingtwo elastomeric members 202(a), 202(b), it will be appreciated that thecartridges sockets 205, 206 may comprise any number of elastomericmembers while remaining within the scope of the present disclosure. Insome embodiments, the sockets 205, 206 may comprise an equal number ofcomponents. In other embodiments, one of the two sockets 205, 206 maycomprise a first number of elastomeric members while the other of thetwo sockets 205, 206 comprises a second number of elastomeric members.In embodiments comprising more than two elastomeric members, more thantwo spacers 222 are inserted into the uncured rubber and the number ofspacers 222, and the number of spacers 222 inserted into the uncuredrubber is based on the desired number of elastomeric members.

In some embodiments, each of the elastomeric members within a socket205, 206 are of substantially equal size. In other embodiments, a socket205, 206 may comprise a plurality of elastomeric members of varioussizes. In some embodiments, at least two elastomeric members within asocket 205, 206 are of substantially equal size. In other embodiments,each elastomeric member within a socket 205, 206 may be a different sizethan all of the other elastomeric members within the socket 205, 206. Insome embodiments, each of the elastomeric members within a socket 205,206 are of substantially equal resilience. In other embodiments, asocket 205, 206 may comprise a plurality of elastomeric members ofvarious resiliencies. In some embodiments, at least two elastomericmembers within a socket 205, 206 are of substantially equal resilience.In other embodiments, each elastomeric member within a socket 205, 206may be a different resilience than all of the other elastomeric memberswithin the socket 205, 206.

In the embodiment depicted in FIGS. 7 and 8, the drivelink 200 does notinclude securing means such as a pin or an adhesive layer. Since theelastomeric members 202(a), 202(b) are vulcanized directly to thehousing 204, they are tightly bonded to the housing 204, therebyeliminating the need for separate securing means. While some embodimentsmay include separate securing means (e.g., pins and/or an adhesivelayer), advantages may be gained through not including securing means.For example, the lack of separate securing means may reduce the amountof components, thereby reducing manufacturing costs. Furthermore, thelack of securing means offers improved operational performance sincestress from such separate components will not be exerted on thedrivelink 200.

In the embodiment depicted in FIGS. 7 and 8, the drivelink 200 may notinclude arcuate portions along the peripheral surfaces of the housing204, elastomeric members 202(a), 202(b), and trunnion races 207, 208.Since the elastomeric members 202(a), 202(b) are vulcanized directly tothe housing 204, they are tightly bonded to the housing 204, therebyeliminating the need for arcuate portions. While some embodiments mayinclude arcuate portions along a surface of at least one of theelastomeric members 202(a), 202(b) and at least one of the housing 204or trunnion races 207, 208, advantages can be gained through the lack ofarcuate portions. For example, without the arcuate portions, the amountof stress exerted on the elastomeric members 202(a), 202(b) by thehousing 204 is reduced.

Turning now to FIG. 9, depicted is a method of providing the housing 104and bearing assembly described herein. Step 300 comprises designing adrivelink 100. During the designing step 300, a calculation may becarried out to determine the expected compression loads that will act onthe drivelink during operation. Based on the expected compression loadsand based on the type of material that will used for the elastomericmembers 102(a), 102(b), a calculation may be carried out to determinethe expected deformation that will be experienced by the elastomericmembers during operation. In step 301, a housing 104 and trunnion races107, 108 may be manufactured and the trunnion races 107, 108 may bedisposed within the housing 104 to form sockets 105, 106. In step 302,the cartridges 101, 111 may be manufactured. The step 302 ofmanufacturing the cartridges 101, 111 may comprise manufacturing theelastomeric members 102(a), 102(b) and manufacturing the races 103(a),103(b). During step 302 (e.g., before pre-compression takes place) theelastomeric members 102(a), 102(b) may be dimensioned to besubstantially equal to the sockets 105, 106 within the housing 104. Theelastomeric members 102(a), 102(b) may be formed and cured separatelyfrom one another. Once the elastomeric members 102(a), 102(b) havecured, in step 303 the elastomeric members 102(a), 102(b) may bepre-loaded. Pre-loading 303 the elastomeric members 102(a), 102(b) maycomprise pre-compressing the elastomeric members a predetermined amount.The amount of pre-compression may correspond to the calculated expecteddeformation. For example, the amount that the elastomeric members102(a), 102(b) are pre-compressed may be equal to the amount of expecteddeformation. The elastomeric members 102(a), 102(b) may be disposedwithin the races 103(a), 103(b) before or after the pre-compression. Instep 304, the pre-loaded cartridges 101, 111 are inserted into thehousing 104. FIG. 10 illustrates the insertion of the cartridges 101,111 into the housing 104.

Since prior to the pre-loading, the size of each cartridge 101, 111 wassubstantially equal to the size of the corresponding socket 105, 106,when the cartridge 101, 111 is inserted into the corresponding socketafter the pre-loading at least one spacing 117 is formed within thecorresponding socket 105, 106. The cartridges 101, 111 may be insertedinto the sockets 105, 106 such that the spacings 117 are located alongan axis perpendicular to the direction of the expected loads.

In step 305, the cartridges 101, 111 are secured within the housing 104via securing means. In step 306, the drivelink 100 is assembled into arotor hub. Step 307 comprises operation of the rotor hub and drivelink100. In operation, the disclosed drivelink 100 provides superiorkinematic performance while experiencing substantially no tension. Sincethe size of the sockets 105, 106 are substantially equal to the size ofthe cartridges 101, 111 prior to the pre-compression, and since theamount the cartridges 101, 111 are pre-compressed is substantially equalto the amount the cartridges 101, 111 are expected to deform uponcompression, the cartridges 101, 111 are configured to react to thecompression by deforming into a shape substantially equal to shape ofthe sockets 105, 106. Thus, when compressed, the size of the firstbearing cartridge 101 is substantially equal to the first socket 105 andthe spacings 117 within the first socket 105 are eliminated. Likewise,when compressed, the size of the second bearing cartridge 111 issubstantially equal to the second socket 106 and the spacings within thesecond socket 106 are eliminated. As a result, the compressed cartridgesoffer improved kinematic properties without experiencing tension.

FIG. 11 illustrates another method of providing the drivelink 200according to the embodiment illustrated in FIGS. 7 and 8. Step 400comprises designing a drivelink 200. During the designing step 400, acalculation may be carried out to determine the expected compressionloads that will act on the drivelink 200 during operation. Based on theexpected compression loads and based on the type of material that willbe used for the first and second pairs of elastomer members 202(a),202(b), a calculation may be carried out to determine the expecteddeformation that will be experienced by the elastomeric members 202(a),202(b) during operation. Step 401 comprises manufacturing trunnion races207, 208 and housing 204, wherein the housing comprises a pair ofsockets 205, 206. Step 402 comprises inserting the first trunnion race207 within the housing and inserting the second trunnion race 208 withinthe housing 204. In step 403, uncured rubber or other elastomericmaterial is introduced into the first socket 205 and into the secondsocket 206. In step 404, a first pair of spacers 222 is inserted intothe first socket 205 and a second pair of spacers 222 is inserted intothe second socket 206. The size of the spacers 222 may be engineered tocreate appropriately sized spacings 217 between the elastomeric members202(a), 202(b). In step 405, a curative is added in order to vulcanizethe rubber. In step 406, the rubber is allowed to cure. After the rubberhas cured, in step 407, the spacers 222 are removed from the sockets205, 206. Upon removal of the spacers, the cured rubber forms a pair ofelastomeric members 202(a), 202(b) separated by a pair of spacings 217previously occupied by the spacers 222. In step 408, the drivelink 200is assembled into a rotor hub. Step 409 comprises operating the rotorhub with the drivelink 200.

At least one embodiment is disclosed and variations, combinations,and/or modifications of the embodiment(s) and/or features of theembodiment(s) made by a person having ordinary skill in the art arewithin the scope of the disclosure. Alternative embodiments that resultfrom combining, integrating, and/or omitting features of theembodiment(s) are also within the scope of the disclosure. Wherenumerical ranges or limitations are expressly stated, such expressranges or limitations should be understood to include iterative rangesor limitations of like magnitude falling within the expressly statedranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4,etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). For example,whenever a numerical range with a lower limit, RI, and an upper limit,R_(u), is disclosed, any number falling within the range is specificallydisclosed. In particular, the following numbers within the range arespecifically disclosed: R=R_(l)+k*(R_(u)−R_(l)), wherein k is a variableranging from 1 percent to 100 percent with a 1 percent increment, i.e.,k is 1 percent, 2 percent, 3 percent, 4 percent, 5 percent, . . . , 50percent, 51 percent, 52 percent, . . . , 95 percent, 96 percent, 97percent, 98 percent, 99 percent, or 100 percent. Unless otherwisestated, the term “about” shall mean plus or minus 10 percent. Of thesubsequent value. Moreover, any numerical range defined by two R numbersas defined in the above is also specifically disclosed. Use of the term“optionally” with respect to any element of a claim means that theelement is required, or alternatively, the element is not required, bothalternatives being within the scope of the claim. Use of broader termssuch as comprises, includes, and having should be understood to providesupport for narrower terms such as consisting of, consisting essentiallyof, and comprised substantially of. Accordingly, the scope of protectionis not limited by the description set out above but is defined by theclaims that follow, that scope including all equivalents of the subjectmatter of the claims. Each and every claim is incorporated as furtherdisclosure into the specification and the claims are embodiment(s) ofthe present invention.

What is claimed is:
 1. A method, comprising: manufacturing trunnionraces and a housing of a drivelink, wherein the housing comprises twosockets, each socket surrounding one of the trunnion races;manufacturing two cartridges, a cartridge corresponding to each socket,wherein each cartridge comprises a first elastomeric member and a secondelastomeric member separated from one another by one or more spacings,wherein the first elastomeric member and the second elastomeric memberare configured to fill a portion of the one or more spacings when thefirst portion undergoes compression when a load is applied to thedrivelink, the first elastomeric member is configured to undergocompression when the load is applied to the drivelink, and the secondelastomeric member is configured to not be in tension when the load isapplied to the drivelink; pre-loading each cartridge in compression;inserting each pre-loaded cartridge into the socket to which thepre-loaded cartridge corresponds in the housing with a radially outersurface of the elastomeric members of each pre-loaded cartridge adjacenta surface of the socket to which the pre-loaded cartridge corresponds,and a radially inner surface of the elastomeric members of eachpre-loaded cartridge adjacent a surface of the corresponding trunnionrace in the socket to which the pre-loaded cartridge corresponds; andsecuring each pre-loaded cartridge within the socket to which thepre-loaded cartridge corresponds in the housing.
 2. The method of claim1, further comprising: assembling the drivelink into a rotor hub; andoperating the rotor hub comprising the drivelink.
 3. The method of claim1, further comprising designing the drivelink based at least in part onexpected compression loads on the drivelink during operation of thedrivelink.
 4. The method of claim 1, further comprising orienting thecartridges inserted into the socket to which the cartridge correspondsin the housing to perpendicularly align the one or more spacings with adirection of expected compressive loads exerted on the drivelink.
 5. Themethod of claim 1, wherein securing each pre-loaded cartridge within thesocket to which the cartridge corresponds in the housing comprisesbonding the radially outer surface of the elastomeric members of eachcartridge with the surface of the socket to which the cartridgecorresponds.
 6. The method of claim 5, wherein bonding the radiallyouter surface of the elastomeric members of each cartridge with thesurface of the socket to which the cartridge corresponds comprisesvulcanizing the radially outer surface of the elastomeric members ofeach cartridge with the surface of the socket to which the cartridgecorresponds.
 7. The method of claim 1, wherein each cartridge comprisesthe elastomeric members of each cartridge and an outer race surroundingthe elastomeric members of each cartridge; and wherein securing eachcartridge within the socket to which the cartridge corresponds in thehousing comprises applying adhesive between the outer race and thesurface of the socket to which the cartridge corresponds.
 8. The methodof claim 1, wherein each cartridge comprises the elastomeric members ofeach cartridge and an outer race surrounding the elastomeric members ofeach cartridge; and wherein securing each cartridge within the socket towhich the cartridge corresponds in the housing comprises: creating anaperture through the housing and a portion of each cartridge; andinserting a pin through the aperture.
 9. The method of claim 1, whereinpre-loading each cartridge in compression comprises compressing eachcartridge substantially equal to an amount each cartridge is expected todeform in compression during operation of the drivelink.
 10. The methodof claim 1, further comprising: forming an arcuate portion in thesurface of the socket of the housing; and forming an arcuate portion inthe radially outer surface of each cartridge corresponding to thearcuate portion in the surface of the socket to which the cartridgecorresponds of the housing.